root: fix macos build (spack#47483)

No ROOT `builtin` should ever be set to true if possible, because that
builds an existing library that spack may not know about.

Furthermore, using `builtin_glew` forces the package to be on, even when
not building x/gl/aqua on macos. This causes build failures.

Caused by spack#45632 (comment) .

var/spack/repos/builtin/packages/root/package.py

@@ -634,7 +634,7 @@ def cmake_args(self):
             define("builtin_freetype", False),
             define("builtin_ftgl", False),
             define("builtin_gl2ps", False),
-            define("builtin_glew", self.spec.satisfies("platform=darwin")),
+            define("builtin_glew", False),
             define("builtin_gsl", False),
             define("builtin_llvm", True),
             define("builtin_lz4", self.spec.satisfies("@6.12.02:6.12")),